Process of purifying glycerin.



No; 654.023. Patented July I7, I900.

E. A.- nucH.

PROCESS OF PUBIFYING GLYGERIN.

'(Appiicntion flld 1350.28, 1897.)

(No Model.)

(swa w m gM m: NORRIS Fans 00,, PHOTDLITHO" WASNINGYON. n. c.

A'IENT PROCESS OF PURIFYING GLYCERIN.

SPECIFICATION forming part of Letters Patent No. 654,023, dated July 17, 1900.

Application filed December 23, 1897.

To all whmn it nuty concern:

Be it known that I, EMILE ALPHONSE RUoH, of the city of Paris, France, have invented Improvements in the Purification of Glycerin, (for which I have obtained Letters Patent in France for fifteen years, dated July 18, 1896, No. 258,190; in Belgium, for twenty years, dated July 18, 1896, No.122,565; in Germany, for fifteen years, dated August 4, 1896, No. 92,803; in England, for fourteen years, dated July 18,1896,No.1,355; in Spain, for twenty years, dated February 1-9, 1897, Vol. 26, fol. 524, No. 20,238, and in Italy, for fifteen years, dated March 31, 1897, Vol. 85, No. 206,)of which the following is a full, clear, and exact description.

On account of glycerin dissolving many mineral salts refiners are compelled to distil same at great cost with expensive apparatus. I have observed that most of the impurities contained in glycerin are formed by certain fatty acids produced during decomposition of any neutral oil or grease into fatty acids and glycerin. These volatile fatty acids by their combination with the bases used to decompose oils or greases form soluble salts and spoil the glycerin. According to my process I first cause the volatile fatty acids to be set free by the addition to diluted glycerin or glycerinous waters of a suitable proportion of any acid, suchas oxalic acid, which will form salts of a greater stability than the salts of volatile fatty acids. An example of the process is as follows: As glycerin contains formates, butyrates of lime, &c., according to the laws of Berthollet, the lime is removed by oxalic acid, which forms an insoluble precipitate of oxylate of lime. The volatile fatty acids are then subjected to a temperature capable of volatilizingviz., about six kilograms steam-pressure-and the water-steam carries them off very easily and entirely. The proportion of oxalic acid added to the glycerin is determined by the equivalent of the fixed bases found in the ashes of a sample of the glycerin. For example, for each fifty six parts of oxid of calcium found one hundred and twenty-six parts of oxalic acid are added, or a little more as the excess disappears in the process of boilling. Any acid forming with the base an insoluble salt Serial No. 663,236. (No specimens.)

or compound may be used, such as sulfuric acid. The acid may be dissolved in the least possible amount of water before it isadded. The addition of the oxalic acid has for its ob ject to set free the combined volatile fatty acids by combining with their bases to form insoluble salts. The liquid is then introduced in the boiler, and by bringing it to boil under eighty-five-pounds pressure per square inch and at the corresponding temperature of 320 Fahrenheit these fatty acids are volatilized and carried away, leaving behind the glycerin that one filtration will deprive of the insoluble mineral salts. The glycerin does not distil over as well as the fatty acids, because the point' of ebullition and volatilization of the glycerin is much higher than the one of the fatty acids. The glycerin distils over in cacao at 360 Fahrenheit for the least and at ordinary pressure or higher pressure at from 560 to 535 Fahrenheit. The glycerin so prepared is then introduced in a boiler or digester, preferably made as will be hereinafter described in reference to the annexed drawing. That apparatus consists of a copper boiler or digester A of any shape able to resist an interior and exterior pressure of eighty-five pounds per square inch. In the drawing this digester has the shape of a long cylinder. This copper. boiler is contained in a double casing made of sheet-iron able to resist a steam-pressure of eighty-five pounds. A worm or steam heating pipe placed inside or outside the digester may be usedin place of or in combination with the double casing.

My boiler or digester is provided with a cover 0, with hole and screw m for cleaning the apparatus; a pipe H, introducing a current of free steam in the boiler, the use of which is explained afterward; an eductionpipe F, with tap to let out steam; a steam gage D; a pipe K, introducing steam into the double casing, and pipe E, letting out steam condensed in double bottom. My boiler is also provided with pipes to fill up and empty same, but they do not appear in my drawing, which serves only to give an idea of construction; but the shape, metal, and fittings can be altered, if convenient, the main feature of the apparatus being that it is constructed so that the glycerin is subjected to any convenient mode of heating while submitted to an injection of steam,thelsteam used for the heating and injection purposes having a pressure of about eighty-five pounds per square inch-- '5. 12., corresponding to a temperature of about 320 Fahrenheit.

The glycerin prepared as explained before is poured into the boiler, which is then hermetically closed, and steam introduced in the double casing B. When steam-pressure in boiler A shows that the temperature of the liquid has raised above 212 Fahrenheit, steam is injected into the glycerin through the pipe H, so as to raise steam-pressure to eighty-five pounds per square inch-21 e., to a pressure corresponding to a temperature of about 320 Fahrenheit. Pipe F is then opened to prod ucea steam circulation through glycerin as large as possible, without, however, decreasing steam-pressure in boiler A. The fatty acids which are set free in glycerin are volatilized by the high steam pressure and mechanically carried out by steam. When glycerin is taken out of boiler-A, the mineral bases remaining in it are easily eliminated by reactions already known (Berthollets laws) and pure glycerin is then obtained, for even if the mineral bases contained in the glycerin were eliminated by the oxalic acid before the treatment in the boiler or without such treatment there would still remain in the glycerin such impurities as the volatile fatty acids. The treatment in the boiler causes these last to be carried away, leaving behind aglycerin requiring only to be filtered to be pure.

With the same apparatus glycerin can be concentrated much more economically than with the use of vacuum and without contact of air by closing pipe H and keeping steampressure in double casing 13.

The advantages of my process are, first, a considerable economy in concentrating and purifying glycerin compared to cost of distillation in vacuo; second, a great saving in the cost of apparatus, and, third, a quality of glycerin which can be easily discolored afterward and which is free from impurities and smell.

I claim-"- it The herein-described process of concentrating and purifying glycerin, which consists in adding an acid to the glycerin capable of precipitating the metallic bases therein, next heating the acidulated glycerin in a steamtight vessel up to a temperature of 320 Fah renheit while submitting it to an injection of steam at the same temperature whereby the separated fatty acids are volatilized, substan* tially as described.

The foregoing specification of my improvements in the purification of glycerin signed by me this 9th day of December, 1897.

EMILE ALPHONSE RUOII.

\Vitnesses:

EDWARD P. MACLEAN, MAURICE HENRI PIGNET. 

